Polymerized Ionic Liquid-Containing Interpenetrating Network Solid Polymer Electrolytes for All-Solid-State Lithium Metal Batteries

The practical application of lithium metal batteries (LMBs) with high energy density is hindered by uneven lithium deposition during battery cycling. To mitigate this process, in this work, an interpenetrating polymer network solid polymer electrolyte (IPN SPE) is prepared by introducing a polymerized ionic liquid (PIL), poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide to a polyhedral oligomeric silsesquioxane-poly(ethylene glycol)-based network SPE. Compared with the virgin SPE, the newly developed IPN SPE exhibited improved ionic conductivity, excellent lithium dendrite resistance, and superior battery performance, which was attributed to the homogeneous, immobilized ion network provided by the PIL-containing IPN. Furthermore, the effects of ionic conductivity and homogenized ion distribution were quantitatively delineated by galvanostatic cycling and polarization measurements at current densities that were below and above the estimated Sand's critical current density based on the Chazalviel model. Full battery tests also showed excellent discharge capacity, cycle life, and Coulombic efficiency. Our results suggest that the PIL-containing IPN SPEs provide a promising system for stabilizing lithium electrodeposition and fabricating high-performance LMBs.